1. Field of the Invention
The present invention relates to magnetic heads for use in magnetic disk or flexible disk devices.
2. Description of the Prior Art
FIG. 48 is a perspective view of an arrangement of a conventional magnetic head such as disclosed in Japanese Patent Application Laid-Open No. 61-39910. In FIG. 48, numeral 1 represents a read/write core having a substantially T-shaped configuration and made of a magnetic material such as a Mn--Zn ferrite, and 2 designates a center core made of a magnetic material similar to that of the read/write core 1. This center core 2 is coupled to the read/write core 1 by a non-magnetic bonding material 3 such as a glass so as to form a read/write gap 4 between the center core 2 and the read/write core 1 on a medium-sliding surface la. Numeral 5 depicts an erase core having a substantially T-shaped configuration and made of a magnetic material such as Mn--Zn ferrite. This erase core 5 is coupled to the center core 2 by a non-magnetic bonding material 6 such as a glass so as to form an erase gap 7 therebetween on a medium-sliding surface 5a. Numeral 8 denotes a back core for closing the magnetic paths made by the read/write core 1, center core 2 and erase core 5, 9 designates a read/write coil wound around a leg 1b of the read/write core 1, 10 is an erase coil wound around a leg 5b of the erase core 5.
The conventional magnetic head shown in FIG. 48 is arranged by an integration of a read/write head formed with a closed magnetic circuit comprising the read/write core 1, back core 8 and center core 2, and an erase head formed with an closed magnetic circuit comprising the erase core 5, back core 8 and center core 2.
FIGS. 49(a) and 49(b) are a top plan view and an elevation side view for describing the flow of a magnetic flux when the magnetic head illustrated in FIG. 48 is taking the reproducing state, where parts corresponding to those in FIG. 48 are marked with the same numerals and characters and the detailed description thereof will be omitted. In the illustrations, (.phi.R), (.phi.R1), (.phi.R2), (.phi.R3) represent the magnetic fluxes of signals to be reproduced through the read/write gap 4, and (.phi.E), (.phi.E1), (.phi.E2), (.phi.E3) designate the magnetic fluxes signals to be reproduced through the erase gap 7.
A description will be made hereinbelow in terms of operation of the above-mentioned conventional magnetic head. In cases where data recorded on a medium (not shown) are reproduced by using the conventional magnetic head, the read/write gap 4 draws a slight leakage flux on the medium so as to form a closed loop of the magnetic fluxes (.phi.R1) and (.phi.R2) passing through the closed magnetic circuit comprising the read/write core 1, back core 8 and center core 2. Here, a portion of the drawn magnetic flux is leaked into the erase core 5 to become a leakage flux (.phi.R3). At this time, the magnetic flux (.phi.R1) passing through the read/write core 1 causes induction to the read/write coil 9 so that the reproduced data signal flows through the read/write coil 9. Further, at this time. in the case that the erase gap 7 is positioned on a track of data to be reproduced or a track adjacent thereto, the erase gap 7 similarly draws a slight leakage flux on the medium so as to form a closed loop of the magnetic fluxes (.phi.E1) and (.phi.E2) passing through the closed circuit comprising the erase core 5, back core 8 and center core 2, a portion thereof being leaked into the read/write core 1 to become a leakage flux (.phi.E3).
According to the conventional magnetic head with the above-described arrangement, in the case of reproducing data recorded on a medium, the magnetic flux (.phi.R1) drawn by the read/write gap 4 and the magnetic flux (.phi.E3) drawn by the erase gap 7 respectively pass through the read/write core 1 so as to cause induction to the read/write coil 9 whereby a signal induced by a superimposed magnetic flux of the magnetic fluxes (.phi.R1) and (.phi.E3) passes through the read/write coil 9 to perform the reproduction. In this case, since the data drawn by the read/write gap 4 are generally different from the data drawn by the erase gap 7, the data drawn by the erase gap 7 result in noises on the reproduced signal from the read/write coil 9 to cause generation of errors and reduction of the margin, thereby lowering the reliability on the reproducing performance of the magnetic head.